a, Serial coronal sections of a renouncing and a persevering mouse centred on the VTA infected with AAV5-EF1a-DIO-ChR2-eYFP and nuclear Hoechst staining (Ho). We infected 109 mice and took coronal images of brains from 71 mice. b, High-magnification images of VTA. c, oDASS perseverance as a function of the infection rate and group data (n = 71 mice, Pearson’s r = 0.075). Infection rate was determined as the number of ChR2–eYFP-positive cells normalized to the total number of cells based on Hoechst staining. Note that mice from which sagittal sections were obtained are not included in this quantification. d, Coronal sections of a renouncing and a persevering mouse that show VTA as above. Sections were additionally stained for tyrosine hydroxylase (TH) using a Cy3-conjugated secondary antibody. Staining was performed in slices from 15 mice. e, High-magnification images of VTA. f, Quantification of TH-positive neurons in the VTA from a subset of renouncing and persevering mice. g, Percentage of TH neurons infected with ChR2. Data are mean ± s.e.m. See Supplementary Table 1 for complete statistics.